An Evidence-Based Checklist of the Damselflies and Dragonflies of Delaware Water Gap National Recreation Area

Olson, William; Barlow, Allen; Halliwell, Thomas; Nixon, George; Wander, Sharon & Wade

An evidence-based checklist of damselflies and dragonflies was compiled for Delaware Water Gap National Recreation Area (DEWA). The checklist of 122 species, based on field surveys conducted from 2007 through 2010, is accompanied by digital photographs of 92 of these species. The Park supports a rich odonate fauna. The most frequently observed species were common whitetail (Plathemis lydia), common green darner (Anax junius), eastern forktail (Ishnura verticalis), widow skimmer (Libellula luctuosa), and spangled skimmer (Libellula cyanea). More than 60 species on the park’s checklist are ranked rare, imperiled, or critically imperiled by one or both state’s (PA or NJ) natural heritage programs. Nineteen species are rare in both states and three of them are globally rare or imperiled: green-faced clubtail (Gomphus viridifrons is G3); New England bluet (Enallagma laterale is G3); and Septima’s clubtail (Gomphus septima delawarensis is G2). DEWA’s diverse aquatic habitats are complimented by riparian fields and forests that adult odonates need for foraging, maturation, and mating. Grassy fields along the Flat Brook and Delaware River, especially near Minisink Island, are utilized by dozens of species and are vital to their conservation. Periodic mowing or controlled burns are beneficial and should be scheduled from mid-October through mid-April, when most of the resident odonates are in the aquatic stage of their lifecycles. Important still-water habitats include high-elevation Sphagnum wetlands on the Kittatinny Ridge. Many of these wetland systems support northern species that are not found elsewhere in the park. Management to control exotic invasive plants is warranted. More fieldwork is needed on the Pennsylvania side of the park to map species’ distributions and to refine abundance estimates. For rare species, more information on post-emergent habitat use would benefit management of riparian areas along the Delaware River and Flat Brook. Key species include brook snaketail (Ophiogomphus aspersus), green-faced clubtail, and Septima’s clubtail.

An Evidence-Based Checklist of the Damselflies and Dragonflies of Delaware Water Gap National Recreation Area

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